A guy is seen working out and then uses the iPhone's camera to measure his heart rate.

It was a particularly interesting addition to the commercial since Apple is rumored to be exploring new ways to incorporate fitness tracking into its devices. Specifically, 9to5Mac has reported that the next version of the iPhone operating system, iOS 8, will have a fitness tracking app called Healthbook.

There have also been reports, like this one from the New York Times, that Apple executives have met with the FDA to discuss its plans to create health monitoring devices, which could include the rumored iWatch wearable computer.

But the big challenge for a fitness app like Healthbook would be hardware. Apple would either need to partner with device makers or create something of its own in order for users to get the most out of fitness tracking. Right now, the iPhone 5S can monitor how many steps you take thanks to a special processor, but that's about it.

Instant Heart Rate, the app featured in Apple's ad, figured out a clever workaround though. You place your finger on the camera lens and the app takes a reading. It costs $1.99.

So, how does it work? Check out some screenshots:

This menu will appear after you download it. Place your finger over the camera lens to start the scanning process.

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The app will scan your pulse. Make sure you stand completely still. If you make one wrong move, the process will take longer.

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After it is complete, the app will deliver the results. It will just be a basic reading of your beats per minute.

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Go to settings at the bottom of the screen. It is the third option. You can set reminders, schedule push alerts, and more. These tools will give you a more thorough reading of your heart rate.

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Instant Heart Rate seems to work as advertised, but there are a few quirks. By sliding your finger over the camera, the app measures your pulse.

It took awhile for the scan to be completed since you had to stand completely still. If you made one wrong move, the process took longer.

Samsung has a similar feature found on the Galaxy S5, but doesn't use the camera. Instead, Samsung built a dedicated heart rate sensor into the phone, next to the camera's flash.